There is evidence that certain dietary deficiencies may lead to necrosis or fat deposition in the liver. Such morphological changes may be a prelude to the eventual development of a neoplastic condition. Therefore, investigations are being pursued on the extent to which the lipotropes choline and methionine inhibit, and vitamin B12 accelerates chemical carcinogenesis. The effects of these substances on chemical carcinogenesis by a variety of carcinogens are to be investigated. In addition, the mutual interactions of the lipotropes and the chemical carcinogens are to be determined.